Highly doped semiconductor material and method of fabrication thereof

Abstract

A method is provided for diffusion doping of semiconductor chips and wafers, in particular silicon chips and wafers, at peak concentrations of greater than about 3×10 19 atoms/cm 3 . The semiconducting material to be doped is placed in a furnace wherein the furnace contains an atmosphere of a carrier gas and a dopant containing gas. The doping containing gas is greater than about 0.1 volume percent of the total volume in the furnace chamber. The pressure of the composite gas is greater than about 0.1 Torr. The composite gas has an oxidizing agent concentration of less than about 1 part per million. The method permits the direct doping of a silicon surface to form a shallow n-doped region having a high peak concentration by a diffusion process thereby eliminating damage to the silicon surface from ion implantation which is the commonly used method to achieve these high doping concentrations. Since the method is nondirectional trench sidewalls can be doped at high concentrations.

We claim: 
     
       1. A method of doping a semiconductor surface with a single dopant species comprises the steps of: providing a gas containing an inert carrier gas and a dopant containing gas;   said gas having a volume and a pressure;   said dopant containing gas being greater than about 0.1% of said volume; and   said pressure being greater than about 0.1 Torr;   said gas having an oxidizing agent concentration of less than about 1 part per million; and   exposing a semiconductor surface to said gas.   
     
     
       2. The method of claim 1, wherein said inert gas is selected from the group consisting of Ar, He, N 2  and H 2 . 
     
     
       3. The method of claim 1, wherein said dopant containing gas is selected from the group consisting of arsine, tertiarybutylarsine, trimethylarsenic, triethylarsenic, phosphine, tertiarybutylphospine, trimethylphosphine, triethylphosphine and diborane. 
     
     
       4. The method of claim 1, wherein the peak concentration of said dopant is greater than about 3×10 19  atoms/cm 3 . 
     
     
       5. The method of claim 1, wherein the depth of said dopant less than about 2,000 Angstroms. 
     
     
       6. The method of claim 1, wherein said semiconductor surface is silicon. 
     
     
       7. The method of claim 1, wherein said semiconductor surface is the surface of a cavity in a semiconductor body. 
     
     
       8. The method of claim 7, wherein said semiconductor body is selected from the group consisting of a semiconductor chip and a semiconductor wafer. 
     
     
       9. The method of claim 1, wherein said method forms the emitter of a bipolar transistor. 
     
     
       10. The method of claim 1, wherein said method forms the source of a FET transistor. 
     
     
       11. The method of claim 2, wherein said method forms the drain of a FET transistor. 
     
     
       12. The method of claim 1, further including polysilicon on said surface and wherein said surface is doped through said polysilicon. 
     
     
       13. The method of claim 1, wherein said surface is a surface of an intrinsic polysilicon layer and wherein said polysilicon layer is substantially uniformly doped. 
     
     
       14. The method of claim 1, wherein said oxidizing agent is selected from the group consisting of oxygen and water. 
     
     
       15. The method of claim 1, wherein said method forms the subcollector of a bipolar transistor. 
     
     
       16. The method of claim 1, wherein said said surface is a surface of a polysilicon layer and wherein said polysilicon is substantially uniformly doped. 
     
     
       17. The method of claim 4, wherein said surface is crystalline. 
     
     
       18. The method of claim 1, wherein said dopant species is an n-dopant. 
     
     
       19. The method of claim 1, wherein said dopant species is a p-dopant. 
     
     
       20. The method of claim 18, wherein said dopant species is arsenic. 
     
     
       21. The method of claim 18, wherein said dopant species is phosphorus. 
     
     
       22. The method of claim 19, wherein said dopant species is boron. 
     
     
       23. A method of singly doping a semiconductor surface with arsenic dopant at a peak dopant concentration of greater than about 3×10 19  atoms/cm 3  comprising: providing a gas containing inert carrier gas an an arsenic containing gas;   said gas having a volume and a pressure;   said arsenic containing gas being greater than about 0.1% of said volume; and   said pressure being greater than about 0.1 Torr;   said gas having an oxidizing agent concentration of less than about 1 part per million; and   exposing a silicon surface to said gas.   
     
     
       24. The method of claim 18, wherein said arsenic containing gas is selected from the group consisting of arsine, tertiarybutylarsine, trimethylarsenic, triethylarsenic, phosphine, tertiarybutylphosphine, trimethylphosphine, triethylphosphine and diborane.